Filming was progressing on The Lord of the Rings: The Fellowship of the Ring in the location of Queenstown when suddenly the town was hit with massive floods and exterior filming had to be suspended. The only available indoor facility that could be used for a studio set was the squash court in a local hotel. Thus, the next day the next scene to be filmed was the intense moment from The Lord of the Rings: The Return of the King when an obsessed Frodo sides with Gollum and sends Sam on his way. Both Elijah Wood and Sean Astin baulked at having to do such a pivotal scene without preparation (Andy Serkis had not been cast at this point so someone from the crew filled in for Gollum) but filming went ahead as planned. Astin's scenes were all successfully completed. The next day, however, the sun came out and the floods abated so exterior filming could resume. The intent was always to return to the squash court (where the set remained standing) to do Elijah Wood's scenes, but, for the next five weeks there was no rain to interrupt exterior filming. At the end of that period, the crew had moved to a new location. Elijah Wood finally got to do his side of the scene one year later in the same location - the squash players of Queenstown had been without a court for that whole amount of time as the set had remained in place on the court the entire period.

The last shot of principal photography was when the newly-crowned Aragorn bows to the four Hobbits. Although Viggo Mortensen did not need to be on set for that day, he nevertheless insisted on attending. He didn't have a crown (it wasn't necessary - he wasn't being filmed) so he fashioned one out of paper. With each successive take, the crown was becoming more ornate and sillier as crew members kept decorating it, so the four actors playing the Hobbits often had difficulty suppressing their giggles.

Billy Boyd (Pippin) sang and composed the tune for the song in Denethor's hall (Tolkien wrote the lyric).

While filming Saruman's death scene (now on the extended DVD), Peter Jackson tried to tell Christopher Lee how to react and breathe after he was stabbed in the back. Lee, a WWII veteran with British special forces, assured the director that he knew what a man sounded like when stabbed in the back.

Lawrence Makoare plays both the Witch King and the orc Gothmog. At one point the two characters exchange dialogue, and later Eowyn fights both (she injures Gothmog, who is then killed trying to attack her, and she kills the Witch King).

Andy Serkis's last day of filming was only a few weeks before the theatrical release. On the carpet of the floor of Peter Jackson's house, they filmed the facial reaction of Smeagol/Gollum when he realizes Frodo intends to destroy the ring. The resulting video was e-mailed to Weta Digital so the animators could replicate the shot with the CGI character.

In the scene when Denethor burns Faramir on the pyre, the pyre could not truly be on fire because Gandalf's horse would not go near it. To solve this, the crew reflected a real fire onto a pane of glass in front of the camera so that it looks as though the pyre is burning.

In the extended cut of the film, the song during the Houses of Healing sequence is sung by Liv Tyler.

Sean Astin tested for the part of Samwise by playing the scene where he cradles the apparently dead Frodo after his encounter with Shelob.

For the moment where Eowyn comforts the dying king Theoden, Miranda Otto had to play most of the scene without her co-star as Bernard Hill had already completed filming all his scenes and had been given a farewell party. Fortunately, when the film-makers realized they wanted to do a little more with the scene, they were able to call on Hill - who was holidaying on New Zealand's South Island - to come back for one more day of filming.